1. Field of the Invention
The present invention relates to technology for accessing storage media, and in particular, to a data writing apparatus and a storage system.
2. Description of the Related Art
In recent years, storage apparatuses using hard disks are becoming essential in various fields, such as those of personal computers, hard disk recorders, video cameras, mobile telephones, and the like. Various specifications are required for the storage apparatuses that use hard disks, according to fields of application; for example, when used in personal computers, high speed and large capacity are required. However, since the quantity of data increases as capacity is enlarged, adequate error correction ability becomes necessary, and it becomes difficult to realize high speed.
Conventionally, turbo encoding, low density parity check encoding, and the like, are used as error correction methods employed in storage apparatuses using hard disks. These error correction methods carry out prescribed processing on data that is an object of error correction encoding, generate parity data, and, on a decoding side, perform a check as to whether or not there is an error, using the parity data, and correct the error. Accordingly, it is necessary that the data and the parity data be linked and written to the storage apparatus. However, since the data and the parity data are generated on separate paths, it is difficult to write the two types of data to the storage apparatus at high speed, while having both of the data types perform a handshake. Furthermore, there are problems in that circuits become complicated and cost becomes high. As a method of improving these problems, there is a method in which parity bits are outputted using vacant time of the data paths after completion of a writing cycle to the storage apparatus. (For example, refer to Patent Document 1).
Patent Document 1: Japanese Patent Application, Laid Open No. 10-340596
However, in general, it is difficult to range in order the data and the parity data, while writing the data that is an object of error correction encoding and the parity data at high speed to the storage apparatus.